Indicators

Related links

Share

On-line version ISSN 1806-907X

Rev. Bras. Anestesiol. vol.55 no.2 Campinas Mar./Apr. 2005

http://dx.doi.org/10.1590/S0034-70942005000200013

CARTAS AO EDITOR

Tracheal intubation of morbidly
obese patients: a useful device

Obese population has considerably increased almost
everywhere. In Brazil, incidence on female population is 13.3% and on male population
is 7%. In Europe and the USA, prevalences are 20% and 22.5%, respectively. Ascension
rate varies from 0.5% to 1% a year in developed countries. Only Japan and The
Netherlands have stable ascension rates 1.

Due to these figures, it is to be expected that
increasingly more obese patients will be seen in our clinical practice, not
only for gastroplasties and gastric bands, but also for different types of procedures.
Several anesthetic peculiarities should be understood to manage such patients.
It can be said that cardiovascular, respiratory and pharmacokinetic changes
are some of the most important. However tracheal intubation (TI) and airway
maintenance were the focus of recent discussions during the latest ASA meeting
in October 2004.

Mallampati index would not be the most effective
factor to predict difficult TI in obese patients. Most successful test for such
evaluation would be neck circumference measurement. So, obese patients would
have 30% probability of difficult TI when neck circumference would be above
60 cm. Only for these cases tracheal intubation with awaken patients would be
recommended 2,3.

It has also been discussed that morbid obesity/difficult
TI ratio is being overvalued 4. Two studies, one with 764 and the
other with 100 morbidly obese patients, were unable to show evident correlation
between body mass index (BMI) and difficult TI 5,6. However, when
obese patients presented obstructive sleep apnea, there has been strong correlation
with difficult TI7. A study has shown the presence of large amounts
of weak paratracheal connective tissue in these patients 8.

This same meeting has stressed that most times
when TI was impossible with direct laryngoscopy, the problem was inadequate
patients' position 3,4 (Figure
1).

Some authors have shown in our journal (Bras
J Anesthesiol) cares to be taken before direct laryngoscopy. Thorough airways
evaluation, pads under shoulders and table bending were considered effective
maneuvers to adequately position these patients, providing thoracic column extension
and cervical column flexion favoring atlanto-occipital joint 9,10 (Figure
2).

Observing recent illustrations published by Bras
J Anesthesiol and after the latest ASA 2004 Refresher Course, I have developed
a single trapezoidal pad. Device was manufactured with density 33 foam and was
wrapped in washable canvas, the measures of which are shown in Figure
5 (Figure 3, Figure
4 and Figure 5).

Note that to correctly position obese patients,
an imaginary line should be drawn between external acoustic meatus and sternum,
and such line should be parallel to the ground 3 (Figure
6).

This single trapeze-shaped device eliminates
the need for numerous folded sheets, blankets and different pillows which would
be needed to obtain such effect. Minor variations could be achieved with small
pillows placed under patient's head (Figure
7).

After careful observation, this TI position may
be also obtained by bending the operating table with headrest parallel to ground.
However not all tables have this facility and for some very obese patients two
tables would have to be adapted to perform the proposed operation.

With our pad, not only TI is made easier, but
also morbidly obese patients' ventilation is more effective as result of distal
shift of breasts and abdomen. Patients themselves, when placed in this position,
very often report easier ventilatory movements.